Had the same issue. I was able to resolve it by logging out with the full set equipped on the character that made the purchase, exiting the client completely, and then restarting. When I logged back in, the set showed up in Collections and I was able to unlock it for my account. I guess this particular set is a bit sluggish when it comes to updating within Collections. Hope this works for you.

/signed I have loads of individual pieces from various Cartel Pack armor sets that I would love to replicate, but the exorbitant cost of completing sets ensures this won't happen. I should think very few people have entire sets of the Cartel Pack armors, making this feature utterly useless for most of the game's population. Implementation is in complete contrast to presentation.

Agreed. This is the first pack I have zero interest in purchasing. Not only because the items are completely underwhelming, but also because BW has dumped yet another recolor of the absolutely useless female dancer outfit. The GTN on Harbinger has had a constant 20+ pages of this garbage since f2p hit, and they've added a set with every pack.